Audio/Video systems have come a long way since the broadcast of the first radio program on Aug. 31, 1920 and since televisions became commercially available in the 1930's. The evolution of multimedia entertainment and communication has been constant and extensive.
In the 1950's, home movies became popular in the United States and elsewhere as Kodak 8 mm film (Pathé 9.5 mm in France) and camera and projector equipment became affordable. Projected with a small, portable movie projector onto a portable screen, often without sound, this system became the first practical home theater. They were generally used to show home movies of family travels and celebrations. Dedicated home cinemas were called screening rooms at the time and were outfitted with 16 mm or even 35 mm projectors for showing commercial films.
Portable home cinemas improved over time with color film, Kodak Super 8 mm film cartridges, and monaural sound but remained awkward and somewhat expensive. The rise of home video in the late 1970s almost completely killed the consumer market for 8 mm film cameras and projectors, as VCRs connected to ordinary televisions provided a simpler and more flexible substitute.
The development of multi-channel audio systems and laserdisc in the 1980s added new dimensions for home cinema. By the early to mid 90's, a typical Home Cinema would have a Laserdisc or S-VHS player fed to a large screen: rear projection for the more affordable setups, and LCD or CRT front projection in the more elaborate. In the 1990s, there were developments such as DVD, 5.1-channel audio, and high-quality video projectors that provide a cinema experience at a price that rivals a big-screen HDTVs sparked a new wave of home cinema interest. In the 2000s, developments such as High Definition video, Blu-ray Disc and newer HD display technologies brought even higher quality Audio/Video (“A/V”) to the general public.
With the proliferation of the quality and quantity of A/V devices (i.e. Media Device) in the home or office also grew the logistic complexity of operating multiple media devices. As opposed to the early days when one would only need to turn on (directly or through a remote control) a television, more advanced media arrangements of the day may include a set of media source devices (e.g. set-top boxes, DVDs, a computers, etc.) and a set of media sink devices (e.g. as multiple displays and one or more audio systems)—each of which may include a separate (remote) control and each of which may require separate operation by a user. In an effort to simply the operation of a multi device media system, there have been efforts to define device to device control signaling protocols which would allow a user to operate multiple devices through a single user interface (e.g. remote control)—for example, AV Link protocol. Another embodiment of device to device controls is found the Consumer Electronics Control (CEC) wiring, which was made mandatory as part of the HDMI standard—although implementation of CEC in a HDMI product is optional. CEC uses the industry standard AV Link protocol for remote control functions over a one-wire bidirectional serial bus. CEC was defined in HDMI Specification 1.0 and updated in HDMI 1.2, HDMI 1.2a, and HDMI 1.3a (added timer and audio commands). The CEC feature is used to allow the user to command and control multiple CEC-enabled boxes with one remote control and for individual CEC-enabled devices to command and control each other without user intervention.
As part of some device to device control signaling protocols or standards, such the AV Link and CEC standard, an acknowledgment (“ACK”) may be required from a device receiving a control signal/command. There may be a time limit (i.e. timeout period) for the ACK to be received. When media devices are connected over wireless data links (e.g. WHDI), travel time of a control signal/command from a device issuing the command to the target device, combined with the travel time of the acknowledgment back to issuing device, may exceed a timeout limit.
There is thus a need for improved methods, circuits, devices and systems for conveying control signaling media devices.